Overview
The dog keeps only a vestige of the clavicle, embedded in a fibrous band (intersectio clavicularis) cranial to the shoulder joint. This intersection divides the muscle in two:
- Cleidobrachialis (m. cleidobrachialis): from the clavicular intersection to the humerus.
- Cleidocephalicus (m. cleidocephalicus): from the clavicular intersection to the head and neck, with a cervical part (pars cervicalis) and a mastoid part (pars mastoidea).
Origin and insertion
- The cleidobrachialis inserts on the cranial surface of the distal end of the humerus.
- The cervical part of the cleidocephalicus reaches the dorsal fibrous raphe of the cranial part of the neck.
- The mastoid part inserts on the mastoid process of the temporal bone.
Action
The main muscle that advances the thoracic limb (shoulder extension). With the limb fixed, it draws the head and neck ventrally and laterally.
Innervation
Accessory nerve and ventral branches of the cervical nerves for the cleidocephalicus; axillary nerve for the cleidobrachialis.
Clinical relevance
It forms the dorsal border of the jugular groove, where the external jugular vein is punctured. It covers the superficial cervical lymph nodes.